The present invention relates to a tumble dryer and here in particular to a domestic tumble dryer as claimed in the preamble of the independent claim.
It repeatedly occurs with tumble dryers that certain small items, such as lint or fluff or other impurities, such as wear material from drive belts, can collect and form deposits in the drum or in the floor region of the housing. On reaching a certain temperature it may occur that these items catch fire. This is to be avoided. In a number of countries, there are already appropriate test procedures in force, or are intended to be brought into effect shortly, such as to prove that fire cannot break out in the tumble dryer. To this end, for example, in the USA as from 2013 tests will be conducted to ensure that a cloth laid over the tumble dryer cannot ignite during the test.
Manufacturers of tumble dryers are therefore concerned with being able to offer tumble dryers whereby a fire in the interior of the tumble dryer can be actively extinguished, or whereby at least the spreading of the fire to the outside can be prevented. In this situation the principle is known from DE 10 2007 061 521 A1 of undertaking active fighting of a fire by extinguishing it with water or other chemicals from a container arranged above the drum, after the extinguishing process has been activated by a temperature sensor. Such a solution, however, is as a rule dependent on a functioning power supply for the operation of the temperature sensor, the control technology and evaluation circuitry relating to it, as well as other devices if appropriate.
As an alternative, passive fighting of a fire is also possible, inasmuch as no easily combustible components made of plastics materials are used any longer, but only fire-resistant plastics, metals, or other materials. This is only possible, however, if increased manufacturing costs are taken into account.
From DE 38 09 754 A1 a fire extinguishing device for tumble dryers is known, as claimed in the preamble of claim 1. A container is provided beneath the worktop, with several cells in which an extinguishing agent is stored. Holes are provided on the underside of the cells, which are closed with the aid of a protective sheath or destructible membrane and are destroyed in the presence of flames or at a temperature above a predetermined limit temperature. Upon the limit temperature being reached, the extinguishing agent is therefore released and falls downwards in order to extinguish the fire which has broken out. According to an alternative embodiment, a container subjected to pressure is provided with an extinguishing agent, from which lines lead to points which are regarded as subject to the risk of fire. In the event of the onset of a fire or the occurrence of a high temperature, the lines can melt and are therefore interrupted and opened respectively. The extinguishing agent is thereby released.
From US 2010/0175898 A1 a fire protection device for a tumble dryer is known, comprising a device for the detection of a temperature inside the tumble dryer. The device is connected to an extinguishing agent releasing device, to which a pulse can be issued by the temperature detection device if a specific temperature is reached. As a result, extinguishing agent can be released by the extinguishing agent releasing device.
The tumble dryers known from the aforecited publications are disadvantageous however in that a relatively large amount of water or extinguishing agent must be retained in order for an outbreak of fire to be reliably extinguished.
It is an object of the present invention to propose a tumble dryer, such as, in particular, a domestic tumble dryer, with which a fire which may break out in the drum or outside cannot spread from the drum and will be extinguished, as far as possible automatically, without a connection to the power supply being necessary. This should be possible with the smallest possible store of extinguishing agent.